Low birth weight and associated infant mortality are issues of great concern for public health policy in the United States. Despite extensive research, it remains unclear why the U.S. has relatively poor birth outcomes when compared to other developed countries. Differences may be due to demographic differences in populations or to differences in health care delivery and financing systems. This study will investigate the relationship between socioeconomic factors and birth outcomes in the United States and France. France was chosen for comparison because it has a large and socioeconomically diverse population, and because it has not been induced in previous comparative studies of birth outcomes. While its health service delivery system is similar to that of the U.S., the health care financing system differs substantially. All pregnant women have health insurance coverage in France. We hypothesize that in both countries poverty does affect outcomes through its negative effect on health status and health behaviors. However, we further hypothesize that the negative effects of poverty are modified in France by the provision of adequate prenatal care of low income women and through the reduction in financial barriers to care. A complex multivariate model will be employed to investigated this issue. Four data sets will be used: two fertility sample surveys (one from each country) and two data bases of all births for selected U.S. and French regions.